1. Technical Field
The invention relates generally to fastening devices. More particularly, the invention relates to a safety snap for securing livestock, and that includes a replaceable shear pin.
2. Description of the Prior Art
It is a well known technique of livestock care to use lead ropes to restrain the animals. These lead ropes are typically secured to the animals with devices known as snaps. For horses, lead ropes or reins are tied to the snap, which is then attached to the halter.
Horses may become frightened or upset, and may attempt to free themselves from the lead ropes. High quality prior art snaps, designed for securing horses, tend to break at near or greater than the weight of the horse. As a result, the horse is often putting its full weight into breaking loose from the restraints. If the horse pulls with sufficient force, the snap breaks. The application of this amount of force can cause the snap to fly through the air. A flying snap has been known to cause severe injury to the animal, to the rider, or to bystanders, including loss of eyes.
On the other hand, if the snap does not break in certain circumstances, the horse may panic and seriously injure itself or its handler. In extreme cases, this can result in death.
Prior art snaps which are designed to break at a lower strength are also subject to various other deficiencies. Their tendency to break increases the cost of fixing or replacing the snap. A broken snap remains attached to the end of the crossties, and can cause injury. If the snap breaks when the rider is in a location at which there are no replacements, the animal must be tied or ridden with the damaged equipment.
Some of the difficulties in using the prior art snaps are detailed in M. Plumb, Curing Cross-Tie Hangups, Michael Plumb's Horse Journal (Sep. 1994), which describes the dangers of using crossties to restrain horses. The article teaches that the most effective and safe crossties use tie materials and snaps that release easily with tension. The theory espoused is that it is safest to the horse and bystanders if the snap and crosstie break easily and quickly. Plumb teaches that the prior art snaps with higher breaking tensions are more dangerous to use when restraining a horse. However, in the event the crossties break, the loose horse would have heavy chains dangling from its halter. If the horse continued to panic, it could inflict damage upon itself and other. This approach can also be quite costly, and inconvenient, for the reasons previously stated.
More recently, a letter published in Michael Plumb's Horse Journal (Nov. 1994) suggests that loops of baling twine or yarn be tied to both sides of the halter, and not to the ends of the ties. The crosstie snap is then attached to the loops. If the horse pulls back, the twine breaks, and the crossties fall to the side. This would avoid the problem of heavy chains dangling from the halter in the event the crossties break. However, none of the other foregoing problems of safely securing crossties to the halter and snap are addressed by the author of this letter.
It would be a significant advance in the art to provide a safety snap which can withstand a higher level of force without increasing the risk of injury to the horse or rider. It would be particularly useful to provide such a safety snap that can be quickly, easily, and inexpensively repaired, that can be adapted to break at different levels of force, and that minimizes the risk of injury to horse and human bystanders.